Latitude adjustment for gyrocompasses



Dec. 9, 1930. R. E. GILLMOR ET AL I A, 1,734,348

LATITUDE ADJUSTMENT FOR GYROCCMPASSES Filed June' 21, 1928 2Sheets-Sheet l INVEN ramszzzaldffijimn. fi amfflegmefi 1930- r R. E.GILLMOR ET AL ,348

LATITUDE ADJUSTMENT FOR GYROCOMPASSES Filed June 21, 1928 2 Shets-Sheec2 I/V VE N T055 1% imic/ffiz llno/r p i drzez'mz.

Patented Dec. 9, 193% UNITED STATES PATENT OFFICE BEGINALD F'. GILLMOB,OF WASHINGTON, DISTRICT OF COLUMBIA, AND RICHARD DEIMEL, 0F HGBOKEN,NEVI JERSEY, ASSIGNORS, BY MESNE ASSIGNMENTS, TO SEER-RY GYROSCOPECOMPANY, INC., 0F BBOOKLYN,-NEW1YORK, A CORPGRATIQN or new Yon]:

Application filed June 2 1,

This invention relates to improvements in gyroscopic compasses,especially of the liquid controlled type wherein a liquid, such asmercury, contained in pair of connected vessels on opposite sides of thegyroscope, is utilized as the gravitational factor. In order to keep theperiod ofthe' compass con stant in different latitudes,it is thepractice to vary the gravitational factor and it has been the practicein the liquid controlled type of compasses to effect this by alteringthecapacity of the connected vessels, or more accurately stated, to alterthe capacity of the co-nnected portions of the vessels (see patent toHarrison and Bawlings, No. 1,362,940, dated December 21, 1920, andpatent to Reginald E. Gillmor, 1,709,395, dated April '16, 1929).

Certain objections have arisen in practice to this method of varying thegravitational factor because it is necessary after the partition hasbeen moved, in the form shown in the Gillmor patent, for instance, tomake sure that the mercury between the vessels is equalized before theauxiliary. connecting valve is closed. This is a-ditiicult procedure at,sea when the ship is rolling, because one can never be certain when themercury has leveled itself. The object of the present in vention is todevise a method of'varying the effective gravitational moment of theliquld without the necessity of a subsequent leveling operat-ion. Wehave found after a number of experiments that the efiectivegravitational torque of the liquid is substantially independent of thedepth of the liquid present but is primarily dependent on the area ofthe free surface of the liquid and its specific gravity.

Accordingly, we propose to vary the free surface of the liquid to alterthe gravitational factor without disturbing the capacity of theconnected portions of the vessels. 2

Referring to the drawings in which several preferred forms of theinvention are disclosed,

Fig. 1 is an elevation, partly in section, of a gyroscopic compassshowing'our invention applied thereto. I i

Fig. 2 is a section at rightangles'to Fig;

LATITUDE ADJUSTMENTFOR GYROCOMPASSES 1928. Serial No. 287,215.

1 of the'sensitive element of the compass showing a modified form of theinvention.

. Fig. 3 is a similar. view of a still further modification.

Fig. i is a section on line 44 of Fig. 3.

Fig. 5 is a view similar to Figs. 2 and 3, showing a still furthermodification.

Fig. 6 is a detailed end elevation of the outside of the vessel of Fig.1, showing the Ineansfor maintaining the center of gravity of thegravitational element.

Fig. .7 is a sectional view of a mercury container showing a modifiedmethod of maintaining the center of gravity fixed by varying the levelof the mercury.

Fig. 8 is a view of a modified method of shifting the weight for thissame purpose,

Fig. 9 is a sectional view of the mercury container showing an automaticmethod of shifting the weight as the wedge is shifted for this purpose.1

In Fig. 1 there is illustrated an ordinary form of liquid controlledgyro compass hav ing the gyroscope proper 1, vertical ring 2, andfollow-up element or phantom 3. On said phantom is pivoted at 4 theframework 4, which supports, the vessels 5 adapted to contain the liquidfor imparting the gravitational moment, the whole constituting what maybe termed the gravitational element or ballistic. Said'vessels are shownas con-. nected by restricted tube or tubes 66, and the frame work isconnected to the bottom of the'gyro compass by'the usual eccentric arm 7whereby both meridian seeking anddamping properties are imparted to thegyro-' scope. To vary the gravitational factor we mount within each ofvessels 5 a movable member 8 which operates to vary the freev surface ofthe mercury 9. In the form'shown in Fig. 1, the member, is in the formof a ,ver-

tically movable wedge having a tapering lower surface 10 adapted toengage the free surface of the mercury and to be lowered thereinto. Itwill be seen that as the wedgeis lowered into the mercury the freesurface of the mercury will be gradually lessened and therebytheoperative gravitational factor of the, compass decreased. For raisingand lowering the wedge, we have shown which may beread in connectionwith a latitude' scale'12. Said stem is threaded in. a rotatable thumbpiece 13 which may beturned to 'raise and lower the wedge. .It will beunderstood that there is a. like wedge 1n the vessel on the oppositeside of the compass.

' The raising and lowering of the wedge,

however, changes slightly the center of p i is occasioned in the centerof gravity within ity of the whole ballistic or gravitational elementcomprising the mounting 4: and the boxes 5 and connected zonta l axis4-4 of the gravitation a]. element and able compensating weight'14-(-Fig:6) which is shown as raised and lowered by a cam rotatably mountedon't-he side of the vessel time on'the scale 12. I v.

' If desired, a means may be. provided to au-' 5 by means such as thegraduated thumb piece 16. The weight is shown as provided with adownwardly-extending stem 17 having a roller 18 hearing on said cam.When adjustin the wedge, therefore, for change inlatitu e, the operatoralso f adjusts the' camql5 so that-the latitude graduations 16 on thedisc 16 -read the same as the latitude graduatomatically shift theweightwhen the'wedge is adjusted vertically; shown inFig. 9. In this-figurethe stem 11 ofthe wedge 8is provided witha disc 20 which engages a camsurface 21 of a plunger 22: Th opposite end of said'plunger engagesoneend of the bellcrank lever 23 having at; the outer end thereof aweiglt fii'. It will readily'be seen that as the wedge is lowered frorn'thfull line'to'the dotted line position that" the weight 24 will be'raised' from the full to the dottedline position without furtheradjustment. By such means the center of gravity can be maintainedapproximately in the desired location.

'Sitill another form of adjusting the auxil i'ary'mass vertically isshown in Fig; 8 wherei in -a cam 15 rotatable in a horizontal plane 7 isshown for raising and lowering the weight 14;. Said cam is shown asmounted ontop Y of box and" may berotated by thumb piece 31,havingpinion 32 on the shaft therewhich engages teeth on the'a-nnularsegof, meat 33-securedto the cam.

' Iii-case,'however, it is desired to maintain the"'center of gravity in'exactl theprop'er position without the necessity oradjusting weights bycams or the like, the form of the inventionshown in Fig.2 may beemployed.

In this figure themain'mercury' vessels are shown at 5'-5" with theusual connecting tube 6. In eachvessel is shown any suitable form ofvertical movable wedge 8. In addiarts includingrthe, mercuryJ This isundesirable as we prefer to keep the center of gravity on thehOIlroscopea We, therefore, provide in" addition a means such asa'vertically shift-1 this purpose.

One such means is tion, we have shown auxiliary mercu vessels 2525{which are not connected, ut in which are "provided similar but invertedwedges Qt -26. The wedges 8 and 26 of the 7 adjacent vessels aresupported on a lever 27 the bracket 29. v 7 Instead of raising andlowering a weight on the system, we may provide auxiliary means forvarying, the interior capacity of the "liquid'containers and'the'rebyadjust the height of. the mercurywiththe raising and lowering of the"wedge." Such'a means is shown inFig. 7 wherein a set .screw'34, providedith' a knurled head 35,*is provided for liqIuid level. I s

: nstead of raising and lowering a wedge to vary the free surface we maymove a member" across the surface of the mercury for this Saidscrew isshown as threaded in the sideof each vessel well below the shown asslidably mounted in a'n'extension 37 i from each box, the plates, beingmounted so that aportionof the same lies below the normal level ofithemercury but with the top of theplateilying above such level. Byturning'thepinion 38 the plate may be advanced more or lessjacross the" surfaceof the mercury to lessen the free surface thereof and by With drawingthe plate completely within its hous ingthe entiresurface of the mercurymay be exposed. In addition to varying thes'urface' of the mercury, itshould be observed that this method also varies the effective lever armof the mercury, since the plate first covers the surface" of the mercuryfarthest from the center of support 44 of the gyroscope 1. This form ofthe-invention also shows the set armsystem'alonefor changes ingravitational moment. Such a form isshown in Fi' s. 3 and 4 wherein aplate 36 is mounted entirely within themercury container on a threadedits shaft 40; 1*Byi'otatingtheshaft the plate is 7 moved toward thecenter of the yroscope which variesthe position of the e ective'or freesurface of the mercury and lessens the effective lever arm of the freesurface therebv varying the gravitational factor. The center of.gravit'yofthesystem in this instance remains u'ncliaiigedwith respect tothe horizontal "a xis i-4', so'that' compensating Weight claim anddesire to secure by Letters Patent has the apparatus shown is onlyillustrative and that the invention can be carried out by other means.Also, while it is designed to use the various features and elements inthe combination and relations described, some ofthese may be altered andothers omitted Without interfering with the more general resultsoutlined, and the invention extends to such use.

Having described our invention, what we 1. In a liquid-controlled gyrocompass, means for varying the gravitational factor comprising a memberadapted to engage the free surface of the liquid, and means for movingsaid member to different positions with respect to said surface to alterthe free surface thereof.

2. In a liquid-controlled gyro compass, means for varying thegravitational factor comprising a member adapted to engage the freesurface of the liquid, means for moving said member to differentpositions with re spect to said surface to alter the free surfacethereof, and adjustable means for keeping the center of gravity of thesystem unchanged. q

3. In a liquid-controlled gyro compass, the

combination with the liquid containers, of a wedge-likev member movablymounted above the normal liquid level, and means for adjusting theheight of said wedge in accordance with the latitude to vary the freesurface of the liquid. 7 l. In a liquid controlled gyro compass, thecombination with the liquid containers, of a wedge-like member movablymounted above the normal liquid level, a. vertically movable mass, meansfor adjusting the height of said we dge in accordance with the latitudeto vary the free surface of the liquid, and means for adjusting saidmass to keep the center of gravity from shifting vertically.

5. In a liquid controlled gyro compass, the combinationwith the liquidcontainers, of a wedge-like member movably mounted above the normalliquid level, a vertically adjustable mass, and a common means foradjusting the height of said wedge in accordance with the latitude tovary the free surface of the liquid and for adjusting said mass to keepthecenter of gravity from shifting vertically.

6. In a liquid controlled gyro compass, the combination with the liquidcontainers, means for varying the gravitational factor comprising amember adapted to engage the free surface of the liquid, means formoving said member to different positions with respect to said surface,and a means for adjusting the interior capacity of said containers tochange the liquid level to compensate for the change in the center ofgravity occasioned by the adjustment of said member.

In testimony whereof we have aflixed our signatures.

" REGINALD E. GILLMOR.

RICHARD F. DEIMEL.

